Compressor and refrigerant play key roles in a refrigeration system. Owing to the de-mands of environment protection, the CFCs and HCFCs refrigerants will be phased out in a short time, and new refrigerants such as R600, R134a and R407C will be used. As the new refrigerant is selected, the motion regularity of the valves will be changed. The motion regularity of the ring valves of a 2-stage refrigerating piston compressor is simulated, and the calculations are done respectively with refrigerants R717 (ammonia), R22 and R134a. The results show that refrigerants and working conditions of a compressor have a direct effect on the motion of the ring valves. Comparing the original design parameters of the ring valves with the modified ones, the former are effective for the HCFC refrigerants, the latter have perfect motion of the valves for the new refrigerants, and the refrigeration system performance parameters, such as input power, the refrigerating quantity and the COP value, are also better. Service life test of the compressor system using the ring valves has been done for R717. The compressor using the modified ring valves has a life exceeding 8000 hours. Hence, the valve design should consider the influences of the refrigerant.